1. Field of the Invention
This invention relates to electronic power supplies and more particularly relates to early power failure detection.
2. Description of the Related Art
With the increasing reliance on electrically powered technology, even a brief power interruption may have highly disruptive effects. This is particularly so in the case of information technology, where important data may be lost, and considerable time may be required to bring the affected systems back on line, with potentially major consequences.
High speed computer systems have the capability to do a significant amount of processing in a matter of milliseconds, enabling some mitigation of the effects of a power interruption during the relatively short period of time that it takes for a power failure to occur, if early warning is provided. It takes a small but finite amount of time, the power supply hold time, for the input power level to decline and the stored energy in the bulk capacitance of the power supply to be exhausted. The earlier the warning of an impending power failure can be provided, the more the system can accomplish by way of mitigation during those precious remaining milliseconds.